The present invention relates to methods and apparatus for assembly of parts, and more particularly concerns the control of relative orientation of parts to be automatically assembled.
In the automatic assembly of many parts, relative part orientation must be controlled so that the parts will interfit as desired. Where parts are assembled under manual control, the assembly operator can visually inspect the parts and take steps to control the desired orientation. For example, in the manufacture of a cassette pulley of the type adapted for use in a magnetic tape cassette handler, the pulley is formed of a flange having a group of projecting assembly pins which are received in corresponding holes of a hub part, and the two parts are firmly secured together. For assembly the two parts must be relatively oriented about the pulley axis in order to enable the flange part pins to be received in the hub part holes. This can be readily achieved in manual or semi-manual assembly by the operator's visual inspection of the part and resulting manual control of orientation. However, for automatic assembly of of such parts, without the necessity of an operator, automatic means is necessary to determine relative orientation of the parts. A typical flange part, has at least a pair of projecting pins which can be utilized for a selected mechanical alignment. However, all external surfaces of the hub part are essentially circular, and thus no mechanical alignment arrangements are readily available. Therefore, completely automatic assembly of such pulley parts has not previously been accomplished.
Accordingly, it is an object of the present invention to provide for automatic orientation sensing in the automatic machine assembly of parts.